Equivalent Circuit Model Extraction for a SAW Resonator: Below and above Room Temperature

Abstract

In this work, a SAW resonator is characterized in terms of admittance (Y-) parameters in the temperature range spanning from 0 °C to 100 °C, with the aim of highlighting how its physical properties are affected by the temperature change. A lumped-element equivalent-circuit model is used to represent the device under test at the considered temperature conditions and a parameters extraction process based on a Lorentzian fitting is developed for the determination of the equivalent-circuit elements in the investigated temperature range. A very good agreement is observed between the performed measurements and the model simulations. The characterization process and the subsequent equivalent-circuit parameters extraction at different temperature values are described and discussed.

Development and Validation of an ANN-Based Approach for Temperature-Dependent Equivalent Circuit Modeling of SAW Resonators

“…The proposed model was verified using the SAW resonator described in Section 2. For this device, the S-parameters were measured for six temperatures in the range from 0 • C to 100 • C, with steps of 20 • C. For each of the analyzed temperatures, the elements of the equivalent circuit model illustrated in Figure 1 were determined using the procedure reported in [26], which is based on a combination of the Lorentzian fitting approach [54] and analytical extraction [22]. These data were used for developing the ANN model.…”

“…The PC served as a central control unit for the measurement setup, allowing for the control of each instrument and the real-time data acquisition and post-processing analysis through the use of custom-made software. A more detailed description of the measurement setup can be found in [ 26 ].…”

“…This is an important aspect of SAW design and optimization, as the temperature-dependent behavior can affect their performance and stability. As the temperature of the SAW device changes, its resonant frequency and Q-factor are affected [ 26 ]. SAW devices are often used in harsh environments, such as industrial or automotive applications, where they are exposed to extreme temperature changes [ 27 ].…”

“…The device is a two-port packaged SAW characterized by a nominal resonant frequency of 423.22 MHz. Unlike the equivalent circuit model [ 26 ], where for each temperature it is necessary to repeat measurements of the S-parameters and extraction of the ECPs, in the present approach the model has ANNs assigned to the equivalent circuit model, aimed at predicting the ECPs for any temperature in the considered range, without the need for additional measurements and optimizations. In that way, a temperature-dependent equivalent circuit model is built.…”

“…In that way, a temperature-dependent equivalent circuit model is built. Firstly, the lumped-element values of the equivalent circuit model for the SAW under test are analytically extracted from the scattering (S-) parameter measurements in the entire range of the investigated temperature [ 26 ]. Next, an ANN is trained by using the extracted values with the aim of generalizing the SAW behavior and calculating the lumped-element values at different operating conditions (i.e., at different temperatures).…”